不同时空尺度下土壤中1.1b-AOA生理生态功能及其物种分化和环境选择适应机制

氨氧化古菌（AOA）是地球硝化过程最重要的驱动者之一。每年约1亿吨氮肥进入农田生态系统，占全球氮输入总量的25%。1.1b类群AOA在土壤硝化微生物中占数量上的绝对优势，且多样性极高。然而土壤中绝大多数1.1b-AOA类群生理生态功能未知，且其在不同时空尺度下的物种分化和环境选择适应机制亦不清楚。这极大制约了对土壤硝化过程微生物学机制的认识。本项目拟选择理化性质具有显著差异的自然土壤和~30年长期定位施肥试验的农田土壤，研究土壤中1.1b-AOA不同类群的生态学分布规律；通过13C-DNA-SIP技术示踪不同类群1.1b-AOA的氨氧化活性，并进行纯菌株的分离培养；通过宏基因组学等手段在不同时空尺度下，解析土壤1.1b-AOA在种内、种间和群落水平的物种分化和环境选择适应机制。研究结果将加深对土壤1.1b-AOA物种多样性形成机制及其对全球氮循环贡献的认识，具有重要的理论和生态环境意义。

Ammonia-oxidizing archaea (AOA) is the major driver of global nitrification. Annually, about 100 Tg of N fertilizer is applied to the agroecosystems, accounting for 25% of global nitrogen inputs. 1.1b group of AOA numerically predominate the soil nitrifying communities, and contain at least 14 phylogenetically different clusters. However, ecophysiological functions of most of the 14 clusters, as well as the species differentiation and evolutionary adaptation of soil 1.1b-AOA are still unclear. Here, natural soils with distinct physicochemical properties and the agricultural soils under ~30 years of different fertilizer applications will be collected to investigate the ecological distribution of the different populations, especially ‘sequence-discrete populations’, of soil 1.1b-AOA. We then use DNA-SIP technique to determine ammonia oxidation activity of different clusters of soil 1.1b-AOA. The representative cultures of each cluster will be also enriched and isolated. The species differentiation and evolutionary adaptation of soil 1.1b-AOA at intra- and inter species, and whole community levels will be revealed by using metagenomic analysis at different temporal and spatial scales. The results will enhance our understanding of the mechanisms underpinning the species diversity of soil 1.1b-AOA and their contribution to the global nitrogen cycling.